Abstract Cocaine abuse remains a major public health problem in the US. Cocaine addiction is a chronic relapsing neurological disorder associated with severe medical and psychosocial complications. The mechanisms of cocaine addiction are poorly understood, and no effective treatment is currently available. A better understanding of the development of addiction is essential for creating effective therapy for cocaine addiction. Our knowledge about cocaine addiction has been generated mostly from studies with animal models, with limited contributions from information about human neuronal pathology obtained by analyzing PET (Positron emission tomography) images and postmortem brain tissues of end-stage cocaine addicts. It has been difficult to obtain differentiated neurons from cocaine addicts for molecular analysis. Patient-derived induced pluripotent stem cells (iPSCs) provide an excellent platform for exploring the mechanisms of cocaine addiction. The purpose of this proposal is to use iPSC-derived the medium spiny neurons (MSNs) in human striatum including nucleus accumbens as a model to investigate the mechanisms of cocaine addiction. Striatal MSNs play key roles in cocaine addiction, and they receive glutamatergic input from prefrontal cortex. Glutamatergic inputs from cortical neurons are required for the synaptogenesis on the striatal MSNs in striatal culture in vitro. Aim 1 is to generate iPSC-derived striatal MSNs and frontal cortical (FC) glutamatergic neurons from both cocaine-dependent patients (CD) and unaffected controls (UC). The iPSC-derived cortical neurons will be engineered to stably express GFP so that they can be identified in co-culture with striatal MSNs, while the iPSC-derived MSNs will be identified by immunostaining with antibodies specific DARPP32, GABA and dopamine receptors (D1R and D2R). Aim 2 is to compare morphological, neurochemical and electrophysiological properties of the iPSC-derived striatal MSNs between the CD and UC groups. This study will generate important tools for cocaine addiction research, and may uncover key morphological, neurochemical and electrophysiological differences between CD and UC. Therefore, it may serve as the foundation for elucidating the molecular and cellular mechanisms of cocaine addiction.